In general, gas insulated switchgears (GIS) relate to power subsystem equipment that improves reliability by storing conductors and various protection devices in a metallic sealed tank and by using an insulating gas that is excellent in insulating performance and arc extinguishing as an insulating medium. Gas insulated switchgears are configured in a complex manner with various components such as breaker, disconnecting switch, grounding switch, etc.
Among the components, circuit breakers are used to safely protect a power system by switching a normal load of a gas insulated switchgear, and by blocking system fault current in an occurrence of abnormal state such as short circuit, grounding, or other accidents of a power line. In circuit breakers, an open operation or a close operation is performed by a fixed electrode and a movable electrode which are connected to each other and interwork therewith.
In addition to gas circuit breakers, vacuum circuit breakers are used. Vacuum circuit breakers are circuit and appliance protecting apparatuses in which an arc generated when switching a normal load or blocking a fault current is extinguished in a vacuum interrupter in order to rapidly separate a circuit. Such a vacuum interrupter, as a key component of a circuit breaker, is configured with a movable contact and a fixed contact which are provided inside an insulated housing with a vacuum state therein, so that an arc generated when switching is performed is rapidly extinguished. Thus, vacuum circuit breakers are used as contacting devices for switching a power system.
Accordingly, in the conventional vacuum interrupter, an open operation and a close operation are performed by the movable contact and the fixed contact which interwork therewith. However, speed in forming and releasing a short circuit is limited since a movable electrode only straightly moves to contact and separate from a fixed electrode that is fixed at one side. Particularly, in a high voltage direct current system, such speed is important since forming and releasing a short circuit in a vacuum interrupter has to be performed at a high speed. However, in a conventional method, there is a limit to increasing speed since the movable electrode only moves to form and release the short circuit.
In order to solve the above problems, a technique in which an electromagnetic force actuator is used for moving a fixed arc contact so that the fixed arc contact and a movable arc contact separate far away from each other is provided. However, it is difficult to quickly move the contact by using the electromagnetic force actuator. In addition, it is problematic in that the fixed arc contact and the movable arc contact have to be controlled in separate mechanisms.
Particularly, due to characteristics of the circuit breaker, performance for rapidly blocking the circuit is very important, thus there is a need to increase blocking speed by relatively moving the fixed contact and the movable contact at a high speed.